Along with recent developments in the performance of ultrasonic diagnostic apparatuses and in the use of a ultrasound diagnostic techniques, ultrasonic diagnostic apparatuses are being utilized in various fields of diagnosis, and a three-dimensional display of an image is now desired in performing a diagnosis using ultrasound. Usually, it was necessary for displaying a three-dimensional image display to collect a plurality of tomographic images of an object to be examined at a plurality of predetermined distances and to reconstruct a three-dimensional image by joining the outlines of an organ or the like which forms an imaging object (observing object) extracted from those tomographic images.
However, when an ultrasonic diagnostic apparatus has a two-dimensional probe, including two-dimensionally arranged transducer elements in a flat surface, and an aperture is formed by concentric multiple rings on the two-dimensional ultrasound probe, the direction of forming an ultrasound beam is limited to the direction of a normal line the probe surface. Accordingly, a three-dimensional image could not be generated by utilizing the above-described combination of ultrasound beams.
Further, because an ultrasonic diagnostic apparatus employing a sparse array technique performs a sector scan with an ultrasound beam without moving the aperture, it is impossible to cross ultrasound beams in the ultrasound measurement. Accordingly, it was impossible to apply a method of generating a tomographic image using a combination of ultrasound beams.
Japanese Unexamined Patent Publication No. Hei. 9-234199 discloses an ultrasonic diagnostic apparatus including an ultrasound probe having a plurality of transducers arranged in a scan direction and a lens direction for transmitting and receiving an ultrasonic wave, which apparatus further includes selecting means for selecting a transducer to be driven from among the plurality of transducers, ultrasound transmitting means for driving the transducer selected by the selecting means in the scan direction and in the lens direction on the basis of predetermined delay data so as to generate a transmitted beam having a focal point at a certain depth in the scan direction and the lens direction, inputting means for inputting information on an object to be examined, and control means for controlling the ultrasound transmitting means in accordance with the information on the object. However, a compound scan using a two-dimensional array probe is not disclosed.
An object of the present invention is to provide a technique with which a tomographic image of high resolution can be collected by means of compound scan while the transducers of a two-dimensional ultrasound transducer array are switched, and to provide a technique with which the image quality can be improved by using a two-dimensional ultrasound transducer array without increasing the scale of the apparatus.